The present invention relates to conveyor systems and, in particular, to a microprocessor-controlled, high-speed conveyor system which includes a plurality of independently controlled branch conveyors, each being coupled to an end-mounted wrapping station. Each branch conveyor is comprised of a controlled source and a feeder conveyor by means of which product is synchronously supplied to a variable-speed wrapping machine at a controlled rate dependent upon the availability of product.
In the manufacture and packaging of products, such as candy bars or bakery goods, it is a general requirement that a conveyor/wrapping system be employed that is compatible with the relatively high output rate of the production equipment. Also, because the production equipment is generally capable of producing product at rates greater than can be accommodated by a single wrapping station, it is typically necessary to have a number of branch conveyor/wrapping machine configurations which cooperate to advantageously handle the expected product flow rates with the least cost and floor space.
High-speed wrapping machines, such as the SUPER-H wrapper manufactured by Doboy Packaging Machinery, Inc. of New Richmond, Wis., allow certain commodities to be wrapped at rates in the range of 400 to 650 products per minute, depending upon the product length. Thus, if the output of a given piece of production equipment is, for example, 1,600 pieces per minute, plural wrapping machines and product conveyors must be integrated into the system to accommodate the higher production rates. Further, the number of wrapping machines employed depends not only on the rate of the production equipment, but also upon the conveyor system, its configuration and its speed of operation.
Branch conveyor systems currently on the market, however, are somewhat deficient in that they are not capable of supplying product at rates compatible with state-of-the-art wrapping machines. Therefore, it is oftentimes necessary to slow the wrapping machines down and not take full advantage of their speed. Also, because branch conveyor systems currently available are not capable of inspecting and rejecting product which is not within specification in terms of size or weight, it can happen that product which does not fall within such specifications is nevertheless wrapped. Prior-art branch conveyors also are not able to readily adjust to random product flow patterns and, as a result, product may arrive at the infeed section of the wrapping machines in an asynchronous fashion. Furthermore, prior art branch conveyor systems are operated under the control of the wrapping machine, independent of product availability. Such an operating condition is deemed to be less efficient than when product availability is also taken into account. It, therefore, has become apparent that it is desirable to have a branch conveyor system that can overcome these and other shortcomings of the prior-art systems so as to more optimally convey product to the wrapping machines.
The present invention comprises a product packaging system having a plurality of branch conveyors and associated wrapping machines, each wrapping machine being supplied sequentially by both a central supply conveyor and a uniquely controlled, laterally-displaced branch source conveyor and branch feeder conveyor combination. The plural branch source and branch feeder conveyors used in the system act in parallel with one another to divert product from the supply conveyor to its associated wrapping machine. In particular, each branch source conveyor operates independently of the others to supply product to be wrapped to its associated wrapping machine as product becomes available from the supply conveyor. If product is not available on the supply conveyor, the affected branch source conveyor and wrapping machine turn off. Each wrapping machine is thereby made the "slave" of its branch source and branch feeder conveyors, and its wrapping speed is varied to accommodate the inventory of available product. Thus, the individual wrapping machines disposed along the supply conveyor operate at varying rates dependent upon product availability.
Each branch conveyor in the system also acts under the control of a microprocessor control system in a unique fashion to inspect and reject product not falling with preprogrammed specifications and to adjust the spacing between products to match that of the infeed conveyor which is a part of the wrapping machine itself. In accordance with the present invention, the branch conveyors are each comprised of a plurality of belted conveyor sections which are mounted in an end-to-end fashion between the supply conveyor and a wrapping machine. Product, e.g., candy bars, is diverted from the supply conveyor to each laterally extending branch, and the first section of the branch, termed the branch source conveyor, receives the product, a row at a time, in a side-to-side orientation transverse to the direction of product flow. The spacing between adjacent rows is controlled by controlling the branch source conveyor speed by means of a microprocessor in a manner which is dependent upon product availability from the supply conveyor. As the individual products traverse the branch source conveyor, they are reoriented into a serial, end-to-end orientation before being redirected 90.degree., via a corner conveyor, to a microprocessor controlled, multisectioned branch feeder conveyor.
At the first section of the branch feeder conveyor, the products are caused to pass at a programmed speed past one or more photoelectric transmitter/receiver inspection stations, where each product is inspected to determine if it meets a plurality of preprogrammed specification parameters. Products not falling within the specification are diverted from the product flow stream by a device responsive to the output from the inspection apparatus.
The products meeting spec next pass to a speed-controlled transition conveyor and then to a controlled backlog conveyor. The speeds of these last-mentioned conveyors are controllably adjusted so as to transport products to downstream conveyor sections with a spacing only approximately corresponding to the spacing of the pusher fingers on the flights of the transfer conveyor of the wrapping machine. The speed of the wrapping machine, in turn, is controlled relative to the availability or inventory of product along the branch feeder conveyor.
Upon leaving the backlog conveyor, the products are transferred to a separation conveyor (shaft-driven from the wrapping machine) where the products are separated from one another a predetermined distance substantially equal to the transfer flight spacing. The products are further positionally corrected at a correction conveyor by determining each product's positional error relative to the center of the transfer flights. Thereafter, a speed-correction signal is produced for each product relative to a preprogrammed base speed ratio (determined during the initial set-up and depending upon the preprogrammed product parameters) so as to control the speed of the correction conveyor and thereby correct the position of each product relative to the transfer flights before transferring the product to a further belted transfer conveyor.
At the belted transfer conveyor, which is also shaft-driven from the wrapping machine, the manner of conveyance of each product changes from a belt-supported condition to a pushed condition, via a plurality of spaced pusher fingers which are attached to a laterally-displaced endless chain. The flights of the chain drive between adjacent fingers, in turn, are set to overlap the flights of the pusher fingers of the wrapping machine's infeed conveyor, and thus each product is synchronously deposited within one of the flights of the infeed chain conveyor without damage to the product.
The present microprocessor control system thus controls each branch source conveyor so as to supply products with a controlled spacing between rows, as determined by the adjustment of the source conveyor's speed, to each branch as it becomes available from the supply conveyor. The sections of each branch feeder conveyor are, in turn, controlled to monitor and reject out-of-tolerance product to correctly position the product relative to the spacing between pusher fingers on the infeed conveyor of the wrapping machine.